Journal of neuroscience methods
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J. Neurosci. Methods · Apr 2011
Intra- and extra-cranial effects of transient blood pressure changes on brain near-infrared spectroscopy (NIRS) measurements.
Brain near-infrared spectroscopy (NIRS) is an emerging neurophysiological tool that combines straightforward activity localization with cost-economy, portability and patient compatibility. NIRS is proving its empirical utility across specific cognitive and emotional paradigms. However, a potential limitation is that it is not only sensitive to haemodynamic changes taking place in the cortex, and task-related cardiovascular responses expressed in the perfusion of extracranial layers may be confounding. ⋯ However when blood pressure was actively manipulated, this effect was absent and replaced by a very large pressure-related response. Our observations demonstrate that blood pressure fluctuations can exert confounding effects on brain NIRS, through expression in extracranial tissues and within the brain itself. We highlight the necessity for continuous blood pressure monitoring alongside brain NIRS, and for further research on methods to correct for physiological confounds.
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J. Neurosci. Methods · Apr 2011
Ipsilateral, cabled sural nerve for a sciatic nerve defect: an experimental model in the rat.
The 10 mm rat sciatic nerve defect model is commonly used to investigate new strategies to improve functional recovery with segmental nerve defects. However, a lack of standardization makes comparisons between studies difficult. The present study aims to evaluate a standardized experimental model that can minimize the number of animals required for obtaining valid results and simulates a current treatment for human peripheral nerve injury defects. ⋯ The results support functional recovery of the sciatic nerve in all grafted animals. The use of an ipsilateral cabled sural nerve graft technique in the rat sciatic nerve defect model is a viable control group that utilizes a single incision, incurs minimal morbidity, and maintains muscle attachments. We conclude that this rat model can be used in various experimental trials in the field of peripheral nerve regeneration.
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J. Neurosci. Methods · Mar 2011
OMP-ZsGreen fluorescent protein transgenic mice for visualisation of olfactory sensory neurons in vivo and in vitro.
Research into the biology of the mammalian olfactory system would be greatly enhanced by transgenic reporter mice with cell-specific fluorescence. To this end we previously generated a mouse whose olfactory ensheathing cells (OECs) express DsRed driven by the S100ß promoter. We present here a transgenic reporter mouse whose olfactory sensory neurons express ZsGreen, driven by the olfactory marker protein (OMP) promoter. ⋯ ZsGreen was expressed along the length of axons providing exceptional detail of the growth cones. The ZsGreen fluorescence was very stable, without fading during frequent imaging. The combination of OMP-ZsGreen and S100ß-DsRed transgenic mice is ideal for developmental studies and neuron-glia assays and they can be bred with mutant mice to dissect the roles of various molecules in neurogenesis, differentiation, axon growth and targeting and other aspects of olfactory sensory neuron and glia biology.
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J. Neurosci. Methods · Jan 2011
Relationship between orientation to a blast and pressure wave propagation inside the rat brain.
Exposure to a blast wave generated during an explosion may result in brain damage and related neurological impairments. Several mechanisms by which the primary blast wave can damage the brain have been proposed, including: (1) a direct effect of the shock wave on the brain causing tissue damage by skull flexure and propagation of stress and shear forces; and (2) an indirect transfer of kinetic energy from the blast, through large blood vessels and cerebrospinal fluid (CSF), to the central nervous system. ⋯ Frontal exposures (head facing blast) resulted in pressure traces of higher amplitude and longer duration, suggesting direct transmission and reflection of the pressure inside the brain (dynamic pressure transfer). The pattern of the pressure wave inside the brain in the head facing away from blast exposures assumes contribution of the static pressure, similar to hydrodynamic pressure to the pressure wave inside the brain.
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J. Neurosci. Methods · Jan 2011
Comparative StudyCerebral arterial gas embolism in swine. Comparison of two sites for air injection.
Cerebral arterial gas embolism is a risk in diving and occurs as a complication in surgery and interventional radiology. Swine models for cerebral arterial gas embolism have been used in the past. However, injection of air into the main artery feeding the pig brain - the ascending pharyngeal artery - might be complicated by the presence of the carotid rete, an arteriolar network at the base of the brain. ⋯ Intracranial pressure, brain oxygen tension and brain lactate correlated after injection of air into the ascending pharyngeal artery, but not after injection into the external carotid artery. Our model is suitable for investigation of cerebral arterial gas embolism. The ascending pharyngeal artery is the most appropriate vessel for air injection.